The present invention relates to a semiconductor device, and more particularly, to a semiconductor device driven by the main power supply voltage and auxiliary power supply voltage.
Semiconductor devices of the related art include a power supply terminal for receiving a main power supply voltage, a switch coupled between the power supply terminal and a power supply node, a first internal circuit driven by the voltage of the power supply terminal, a second internal circuit driven by the voltage of the power supply node, and an auxiliary power supply coupled to the power supply node.
When the main power supply voltage is supplied, the switch is turned on. The first and second internal circuits are driven by the main power supply voltage. At the same time, the auxiliary power supply is charged. If the main power supply voltage is interrupted, the operation of the first internal circuit is stopped and the switch is turned off. Then, the second internal circuit is driven by the auxiliary power supply voltage (see, for example, Japanese Unexamined Patent Publication No. Hei 9 (1996)-235077).